The present invention relates to a termination assembly for a steel tube umbilical and in particular to a termination assembly having improved means for anchoring steel tubes of the umbilical to a termination and to a method of forming a termination assembly.
An umbilical consists of a group of one or more types of elongate active umbilical elements, such as electrical cables, optical fibre cables and fluid conveying conduits, cabled together for flexibility and over-sheathed and/or armoured for mechanical strength. Umbilicals are typically used for transmitting power, signals and fluids (for example for fluid injection, hydraulic power, gas release, etc.) to and from a subsea installation. The main fluid conduits used for manufacturing umbilical are thermoplastic hoses and steel tubes. API (American Petroleum Institute) 17E “Specification for Subsea Umbilicals”, third edition, July 2003, provides standards for the design and manufacture of such umbilicals.
A steel tube umbilical is defined as an umbilical wherein all or most of the elongated umbilical elements which compose the umbilical are steel tubes. The steel tubes and the other elongated umbilical elements that make up the umbilical are grouped together and wound in a helical pattern. Examples of steel tube umbilical are disclosed in the documents U.S. Pat. No. 6,472,614, WO93/17176 and GB2316990. Steel tubes are not permeable to gases. They are also able to resist installation and in-service axial loads, and high external collapse pressures, therefore the umbilical, with judicious design, is able to withstand axial loads without requiring the addition of tensile armour layers. It is also possible to increase further its axial resistance by adding internal steel or composite rods inside the bundle (for example see U.S. Pat. No. 6,472,614 and WO2005/124213).
U.S. Pat. No. 6,102,077 discloses an elongated subsea structure combining the functions of a flexible pipe and of an umbilical. This structure comprises a large diameter central flexible pipe used as a production line for conveying oil or gas, and a plurality of small diameter peripheral pipes arrayed in helical or S/Z manner around the central flexible pipe, said peripheral pipes being used as service or control lines for fluid injection, gas lift injection, hydraulic power or gas release. Such structures are known under the names ISU® “Integrated Subsea Umbilical” and IPB “Integrated Production Bundle”. The central flexible pipe generally complies with the standard API 17J “Specification for Unbonded Flexible Pipe”, second edition, November 1999. The small diameter peripheral pipes of ISU® and IPB are generally steel tubes.